Adaptive network for automated first break picking of seismic refraction events and method of operating the same
First Claim
1. A method for operating an adaptive network to determine a first break in recorded seismic data comprising:
- operating a seismic source to generate seismic vibrations;
detecting said seismic vibrations at a plurality of surface locations;
recording the detected seismic vibrations as a plurality of traces;
storing data representing said plurality of traces in a memory;
retrieving a selected portion of said stored data representing a first trace corresponding to vibrations detected at a first surface location, and in which a first break occurs, and a plurality of neighboring traces corresponding to vibrations detected at a plurality of surface locations near said first surface location and in substantially the same direction from said seismic source as said first surface location, over a period of time including an analysis time;
presenting said retrieved selected portion of said stored data to input nodes of said adaptive network;
operating said adaptive network to produce an output indicating whether or not the analysis time corresponds to the time at which said first break occurs in said first trace;
responsive to the output of said adaptive network indicating that the analysis time does not correspond to the time at which said first break occurs in said first trace, adjusting said analysis time; and
repeating said retrieving, presenting and operating steps for a portion of said stored data representing said first trace and said plurality of neighboring traces over a period of time including the adjusted analysis time.
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Abstract
An adaptive, or neural, network and a method of operating the same is disclosed which is particularly adapted for performing first break analysis for seismic shot records. The adaptive network is first trained according to the generalized delta rule. The disclosed training method includes selection of the seismic trace with the highest error, where the backpropagation is performed according to the error of this worst trace. The learning and momentum factors in the generalized delta rule are adjusted according to the value of the worst error, so that the learning and momentum factors increase as the error decreases. The training method further includes detection of slow convergence regions, and methods for escaping such regions including restoration of previously trimmed dormant links, renormalization of the weighting factor values, and the addition of new layers to the network. The network, after the addition of a new layer, includes links between nodes which skip the hidden layer. The error value used in the backpropagation is reduced from that actually calculated, by adjusting the desired output value, in order to reduce the growth of the weighting factors. After the training of the network, data corresponding to an average of the graphical display of a portion of the shot record, including multiple traces over a period of time, is provided to the network. The time of interest of the data is incremented until such time as the network indicates that the time of interest equals the first break time. The analysis may be repeated for all of the traces in the shot record.
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Citations
10 Claims
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1. A method for operating an adaptive network to determine a first break in recorded seismic data comprising:
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operating a seismic source to generate seismic vibrations; detecting said seismic vibrations at a plurality of surface locations; recording the detected seismic vibrations as a plurality of traces; storing data representing said plurality of traces in a memory; retrieving a selected portion of said stored data representing a first trace corresponding to vibrations detected at a first surface location, and in which a first break occurs, and a plurality of neighboring traces corresponding to vibrations detected at a plurality of surface locations near said first surface location and in substantially the same direction from said seismic source as said first surface location, over a period of time including an analysis time; presenting said retrieved selected portion of said stored data to input nodes of said adaptive network; operating said adaptive network to produce an output indicating whether or not the analysis time corresponds to the time at which said first break occurs in said first trace; responsive to the output of said adaptive network indicating that the analysis time does not correspond to the time at which said first break occurs in said first trace, adjusting said analysis time; and repeating said retrieving, presenting and operating steps for a portion of said stored data representing said first trace and said plurality of neighboring traces over a period of time including the adjusted analysis time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification